多元合金化大断面球墨铸铁组织和性能的分析

为了提升大断面球墨铸铁综合力学性能，通过复合添加微量合金元素铜、锑、锡、钼对大断面球墨铸铁进行微合金化处理，借助金相显微镜(OM)、扫描电子显微镜(SEM)及力学性能测试等手段，研究了Cu Sb Sn Mo复合微合金化大断面球墨铸铁微观组织和力学性能。结果表明，试验球墨铸铁具有良好的综合力学性能。大断面球墨铸铁中添加铜、锑、锡、钼后优化了材料的组织结构，基体组织为珠光体＋少量牛眼状铁素体；试样石墨组织细小、圆整，分布均匀。同时，合金元素的复合加入使得其抗拉强度达到800 MPa以上，硬度约为280HB，伸长率达到5%以上。拉伸断口分析表明，微合金化大断面球墨铸铁断裂模式以解理断裂为主，伴有少量的塑性变形。

Analysis on microstructure and properties of multi alloyed heavy section ductile cast iron

In order to enhance the comprehensive mechanical properties of heavy section ductile iron, small amounts of alloying elements Cu, Sb, Sn and Mo were added in the production of heavy section ductile iron, and the microstructure and mechanical properties of the Cu Sb Sn Mo multicomponent composite micro alloyed heavy section ductile iron was investigated by means of optical microscopy(OM), scanning electron microscopy(SEM) and testing of mechanical properties. The results showed that the multicomponent composite micro alloyed heavy section ductile iron had a better comprehensive performance. The microstructure of heavy section ductile iron was optimized after adding Cu, Sb, Sn and Mo, the microstructure of ductile iron was composed of pearlite, nodular graphite and a small amount of ferrite, and the graphite ball was fine and round, uniformly distributed in the whole section. Meanwhile, the composite addition of alloying elements resulted in a tensile strength (Rm) of 800 MPa or more, a hardness (HB) of about 280, and an elongation rate (A) of above 5% or more. The analysis results of fracture section suggested that the fracture behavior of the multicomponent composite micro alloyed heavy section ductile iron was dominated by cleavage fracture along with a small amount of plastic deformation.